1. Field of the Invention
The invention relates to ink cartridges and ink supply systems.
2. Description of Related Art
A known ink-jet image recording apparatus has a recording head and an ink supply system configured to supply ink to the recording head. The known ink supply system has a known cartridge mounting portion, and a known ink cartridge is configured to be mounted to the cartridge mounting portion. The known ink cartridge has a case, and the case has an ink chamber formed therein. The ink chamber is configured to store ink therein. The known ink cartridge has an ink supply portion, and ink is supplied from an interior of the ink chamber to an exterior of the ink chamber via the ink supply portion.
The known ink cartridge also has an air communication portion, and air is introduced into the interior of the ink chamber via the air communication portion. When the known ink cartridge is mounted to the ink supply device, ink stored in the ink chamber is supplied to the recording head via the ink supply portion while air is introduced into the interior of the ink chamber via the air communication portion. The recording head is configured to selectively eject ink toward a sheet of paper, such that an image is recorded on the sheet.
Another known ink cartridge, e.g., the ink cartridge described in JP-A-2007-144808, has a case, and an ink supply portion and an air communication portion positioned at a side face of the case. The ink supply portion has a supply valve configured to cover and uncover an ink supply opening formed through the ink supply portion. The supply valve is resiliently biased toward the ink supply opening by a resilient member made of resin. Therefore, when the ink cartridge is not mounted to a cartridge mounting portion, the ink supply opening is covered by the supply valve. When the ink cartridge is mounted to the cartridge mounting portion, an ink tube of the cartridge mounting portion is inserted into the ink supply opening. The supply valve moves away from the ink supply opening while receiving a pressing force from the ink tube. Ink is supplied from the interior of the ink chamber to the recording head via the ink tube inserted into the ink supply opening. The air communication portion has an air valve configured to cover and uncover an air communication opening formed through the air communication portion. The air valve is resiliently biased toward the air communication opening by a resilient member made of resin.
In the known ink cartridge, when the ink cartridge is not mounted to the cartridge mounting portion, the air communication opening is covered by the air valve. When the ink cartridge is mounted to the cartridge mounting portion, the air valve receives a pressing force from the cartridge mounting portion, and the valve moves away from air communication opening. Consequently, air flows into the interior of the ink chamber through the air communication opening, and ink is supplied via the ink supply portion smoothly.
The supply valve and the air valve receive a first biasing force and a second biasing force from the resilient members, respectively. The first biasing force is equal to the second biasing force. Therefore, when the ink cartridge is mounted to the cartridge mounting portion, the side face of the case extends in the gravitational direction, such that the ink supply opening is positioned at the lowermost position with respect to the surface of ink stored in the ink chamber, and hence ink may leak via the ink supply opening.
When the first biasing force and the second biasing force are set to be relatively weak, a user may easily mount the ink cartridge to the cartridge mounting portion because a force which the user receives from the resilient members are relatively weak. Nevertheless, ink may leak from the ink supply opening because the supply valve may not cover the ink supply opening reliably. In contrast, when the first biasing force and the second biasing force are set to be relatively strong, the supply valve may cover the ink supply opening reliably. Nevertheless, the user may have a difficulty in mounting the ink cartridge to the cartridge mounting portion because the user receives a relatively strong force from the resilient members. If different resilient members are used for biasing the supply valve and biasing the air valve, an operator may improperly install the incorrect resilient members when the ink cartridge is manufactured. The assembly work of the ink cartridge may become complicated.